1. Field of the Invention
The present invention relates to an apparatus for excavating a hole by sucking debris and spoil out of the
2. Discussion of Background
Such an apparatus is shown for example in German utility model DE 29902562 U1 which discloses a vehicle with a suction tube to be inserted into a hole or excavation to suck debris and spoil out of the hole, an air pump to cause the suction and a filter to remove the spoil from the airflow.
Excavating holes using a suction excavator as in the above German utility model is advantageous because holes with a much smaller horizontal cross-section can be dug using this device than previous excavations made using drills, spades etc. Excavating using a suction excavator is much quicker than conventional digging techniques, reduces the amount of spoil produced from the hole and the amount of tarmac required to re-fill the hole, causes less damage to tree roots and to other utility pipes and cables and causes much less disruption to pedestrians and drivers if used in a street. However, because of the large volume of air that is sucked through the vehicle, any fuel gas from a leaking gas main for example is likely to be sucked into the vehicle. Any sparks produced within the vehicle, for example from the air pump or static build-up within the vehicle due to the fast movement of air through pipes etc., is likely to cause a spark, igniting the gas and causing an explosion.
According to a first aspect of the present invention there is provided a suction excavator with a gas sensor arranged to detect for the presence of gas in the passage of air through the suction excavator.
The provision of a gas sensor within the suction excavator enables the presence of potentially dangerous explosive gas within the suction excavator to be determined so that appropriate action can be taken.
There is preferably provided a control means which when gas is detected flushes air through the suction excavator.
All of the components of the suction excavator through which suction air is passed, such as the air pump, suction tube etc., are preferably electrically bonded to each other and a connection between the connected components and earth provided to discharge any electrostatic charge built-up. The bonded components may be connected to earth via electrostatically conducting tyres when the suction excavator is mounted on a vehicle or via an electrically conducting strap, for example.